A hard disk drive typically contains one or more disks clamped to a rotatable spindle motor, at least one head for reading data from and/or writing data to the surfaces of each disk, and an actuator utilizing linear or rotary motion for positioning the head(s) over selected data tracks on the disk(s). The actuator positions the read/write head over the surface of the disk as the spindle motor rotates and spins the disk. An air bearing forms between the read/write head and the disk surface so that the read/write head follows the contours of the disk without impinging on the disk surface.
Contamination may be introduced to the recording medium via a number of sources. For example, oil can leak from a bearing or moving parts can collide to form debris left on the disk surface. As the read/write head traverses the disk surface, it can potentially collide with the debris or the debris can collect on the underside of the slider, potentially leading to writing and/or reading errors. Where an error is detected, a hard disk drive can often perform corrective steps to ensure that data is not lost or contaminated.